Unit 4: Chemistry

UNIT 4
 STANDARDS:
 STATE OBJECTIVES: NCES 2.1.1, 2.1.3, 2.1.4
 LESSON 1
States of Matter
 Solid
 Definite shape Definite Volume.
 Liquid
 Definite volume, NO definite shape.
Crystalline structure
Takes shape of container
 Gas
 No definite shape, No definite
volume. Has volume and shape of
container.
 Plasma
 Temps of 5000oC
 Ionized gases
 Found in stars, or plasma furnaces
Change of State
 Melting
 Solid to liquid. + Heat
 Freezing
 Liquid to Solid. - Heat
 Evaporation
 Liquid to Gas. + Heat
 Condensation
 Gas to Liquid. - Heat
 Sublimation
 Solid to Gas. + Heat
You must be able to identify and give examples
Basic Chemistry Terms
 Element
 Examples
 Hydrogen
 Helium
 Gold
 Lead
 Xenon
 A substance that
cannot be broken
down into simpler
substances by
physical or chemical
means.
 There are 92
naturally occurring
elements
Atoms
 What is an atom?
 An atom is the
smallest part of an
element that has all
of the particles of
the element.
Early Atomic Theory
 Democritus
 Greece 460 - 370 B.C
 World composed of 2
things

Empty Space
 Tiny particles called
atomos
The word atomos in
Greek means “invisible”
Aristotle
 Atomic Theory
 Greece 384-322 B.C.
 Came AFTER Democritus
 Believed all mater was
continuous and composed
of only one material
 The material of all matter
was hyle (the essence)
 This theory was
accepted until the 17th
century
Antoine Lavoisier (1743-1794)
 Law of Conservation
of Mass
 Observed chemical
reactions in a closed
container (system)
 The Law of
Conservation of mass
states, “matter can
neither be created nor
destroyed” and the
mass of the reactants
must equal the mass of
the products.
Determining the Atomic Parts
 J.J. Thompson
 1856-1940
 Performed experiments
to determine the
structure or charged
parts of the atom.
 Used a cathode-ray
tube to determine that
the atom was
composed of mainly
empty space
 Credited with the
discovery of the
electron.
Robert Millikan (1868-1953)
 “Oil-Drop”
experiment
 With a simple
experiment was able to
detemine the “relative”
charge of the electron
 Measured the force of a
tiny charged droplet of
oil suspended against
gravity between two
electrodes (+ and -)
Ernest Rutherford (18711937)
 “Gold Foil”
Experiment
 Lead to Modern Day
Model of the Atom
 Shot a cathode ray into
a gold foil and noticed a
deflection of the beam
 Deduced there was
something in the atom
that was deflecting the
beam
 Called it a nucleus
 Nucleus orbited by
electrons
Rutherford-Bohr Model
 Atomic Model
 Represents the
overall structure of
the atom
 Nucleus in Center
containing protons
and neutrons
 Electrons make up
the cloud around the
nucleus and have
defined
arrangements
Parts of the Atom Summary
 Nucleus
 Center part of the atom
 Contains the majority of the
atom’s mass
 Electron Cloud  Contains the electrons
 Divided into energy levels
 Involved in chemical
bonding
Subatomic Particles Review
 Proton
 Positive charge
 Counts for atomic number
 Part of atomic mass
 Neutron
 Neutral Charge
 Part of atomic mass
 Electron
 Negative charge
 Negligible mass
 Equal to protons to give neutral
charge of element
Understanding the Element
 Element
 Symbol
 Atomic Number
 Atomic Mass
 See previous defn.
 Shorthand way of
representing element
 Number of protons
present in the nucleus
 Sum of protons and
neutrons in the nucleus
Example of typical Element
Identify each part of the picture above (A, B, C, D)
The Periodic Table
Family Number
P
E
R
I
O
D
Student Periodic lab
 Stop and perform the simple periodic table
lab. This is an in class assignment.
 Overall Concept:
 Atoms are arranged in families (vertical) based on
valence electrons and thus how they react.
 Each period (across) represents a different
energy level. Remember only the valence
electrons react.
Energy Levels
 What is an Energy
Level
 The area of an atom
where an electron is
likely to be found.
 Cannot give exact
location of the
electron
 Multiple Electrons
are distributed over
multiple energy
levels
Electrons go to Grade school
 Look at the periodic
table as we discuss
energy levels
 Always remember you
start in First grade,
meet the requirements
and move to second.
 BUT
 To get to the second
grade, you had to meet
the requirements for
First grade and then
move to second
Valence electrons
 What are Valence
Electrons
 Electrons in the
outer most energy
level
 Electrons
 Bonus: VSPER
 Valence Shell Electron
Pair Electron Repulsion
responsible for
forming chemical
bonds
And the number shall be “8”
 How do elements
combine
 What is an Ion
 Elements combine
to gather 8 electrons
in the outer energy
level.
 Atoms gain or lose
electrons to form ion
 A charged particle
 Either Positive or
negative
Getting to 8, Gain or Lose
 Lose Electron(s) =
Positive Charge
 Charge of electron –1
 0 – (–1) = +1
 Range 0 to +4
 Gain Electron(s) =
Negative Charge
 Charge of electron –1
 0 + (–1) = -1
 Range 0 to -4
Getting to 8, Gain or Lose
8
7
G
A
I
N
1
6
2
+
L
O
S
E
-
3
5
4
Remember electrons are like pounds…
Gaining pounds gives negative self image
Losing pounds gives positive self image
Lesson Review
 Name 3 particles that make up an atom
 Define atomic mass
 Describe the characteristic of metal ions
 How is the periodic table arranged
 What happens to size as the atomic number
increases
 How many electrons does a neutral
compound want to have in the outer level